Really? How does a course about developing an operating system not have anything to do with operating system development?

Because the end product doesn't seem to be an operating system by any reasonable definition. The code is basically just a collection of I/O functions that can be called by other kernel-level code.

Not that that's not a useful starting point for low-level hacking, but it's really a stretch to call it an OS given that there's no hint of anything like memory management, task management, hardware abstraction, or any notion of user-level processes that are distinct from the OS itself. Fiddling with GPIOs and writing data to video RAM is great for instant gratification, but it's probably the least interesting part of even a toy operating system.

He's saying it's not a course about developing an operating system, and I agree. It's certainly useful in that it lays some of the necessary groundwork though.